On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment

Abstract Using GFDL's new coupled model SPEAR, we have developed a decadal coupled reanalysis/initialization system (DCIS) that does not use subsurface ocean observations. In DCIS, the winds and temperature in the atmosphere, along with sea surface temperature (SST), are restored to observation...

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Autores principales:	Xiaosong Yang, Thomas L. Delworth, Fanrong Zeng, Liping Zhang, William F. Cooke, Matthew J. Harrison, Anthony Rosati, Seth Underwood, Gilbert P. Compo, Chesley McColl
Formato:	article
Lenguaje:	EN
Publicado:	American Geophysical Union (AGU) 2021
Materias:	decadal prediction coupled initialization data assimilation AMOC model development forecast assessment Physical geography GB3-5030 Oceanography GC1-1581
Acceso en línea:	https://doaj.org/article/8a54f3ef068a4f40bb7e718d367989a2
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spelling	oai:doaj.org-article:8a54f3ef068a4f40bb7e718d367989a22021-11-30T08:40:32ZOn the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment1942-246610.1029/2021MS002529https://doaj.org/article/8a54f3ef068a4f40bb7e718d367989a22021-11-01T00:00:00Zhttps://doi.org/10.1029/2021MS002529https://doaj.org/toc/1942-2466Abstract Using GFDL's new coupled model SPEAR, we have developed a decadal coupled reanalysis/initialization system (DCIS) that does not use subsurface ocean observations. In DCIS, the winds and temperature in the atmosphere, along with sea surface temperature (SST), are restored to observations. Under this approach the ocean component of the coupled model experiences a sequence of surface heat and momentum fluxes that are similar to observations. DCIS offers two initialization approaches, called A1 and A2, which differ only in the atmospheric forcing from observations. In A1, the atmospheric winds/temperature are restored toward the JRA reanalysis; in A2, surface pressure observations are assimilated in the model. Two sets of coupled reanalyses have been completed during 1961–2019 using A1 and A2, and they show very similar multi‐decadal variations of the Atlantic Meridional Overturning Circulation (AMOC). Two sets of retrospective decadal forecasts were then conducted using initial conditions from the A1 and A2 reanalyses. In comparison with previous prediction system CM2.1, SPEAR‐A1/A2 shows comparable skill of predicting the North Atlantic subpolar gyre SST, which is highly correlated with initial values of AMOC at all lead years. SPEAR‐A1 significantly outperforms CM2.1 in predicting multi‐decadal SST trends in the Southern Ocean (SO). Both A1 and A2 have skillful prediction of Sahel precipitation and the associated ITCZ shift. The prediction skill of SST is generally lower in A2 than A1 especially over SO presumably due to the sparse surface pressure observations.Xiaosong YangThomas L. DelworthFanrong ZengLiping ZhangWilliam F. CookeMatthew J. HarrisonAnthony RosatiSeth UnderwoodGilbert P. CompoChesley McCollAmerican Geophysical Union (AGU)articledecadal predictioncoupled initializationdata assimilationAMOCmodel developmentforecast assessmentPhysical geographyGB3-5030OceanographyGC1-1581ENJournal of Advances in Modeling Earth Systems, Vol 13, Iss 11, Pp n/a-n/a (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	decadal prediction coupled initialization data assimilation AMOC model development forecast assessment Physical geography GB3-5030 Oceanography GC1-1581
spellingShingle	decadal prediction coupled initialization data assimilation AMOC model development forecast assessment Physical geography GB3-5030 Oceanography GC1-1581 Xiaosong Yang Thomas L. Delworth Fanrong Zeng Liping Zhang William F. Cooke Matthew J. Harrison Anthony Rosati Seth Underwood Gilbert P. Compo Chesley McColl On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
description	Abstract Using GFDL's new coupled model SPEAR, we have developed a decadal coupled reanalysis/initialization system (DCIS) that does not use subsurface ocean observations. In DCIS, the winds and temperature in the atmosphere, along with sea surface temperature (SST), are restored to observations. Under this approach the ocean component of the coupled model experiences a sequence of surface heat and momentum fluxes that are similar to observations. DCIS offers two initialization approaches, called A1 and A2, which differ only in the atmospheric forcing from observations. In A1, the atmospheric winds/temperature are restored toward the JRA reanalysis; in A2, surface pressure observations are assimilated in the model. Two sets of coupled reanalyses have been completed during 1961–2019 using A1 and A2, and they show very similar multi‐decadal variations of the Atlantic Meridional Overturning Circulation (AMOC). Two sets of retrospective decadal forecasts were then conducted using initial conditions from the A1 and A2 reanalyses. In comparison with previous prediction system CM2.1, SPEAR‐A1/A2 shows comparable skill of predicting the North Atlantic subpolar gyre SST, which is highly correlated with initial values of AMOC at all lead years. SPEAR‐A1 significantly outperforms CM2.1 in predicting multi‐decadal SST trends in the Southern Ocean (SO). Both A1 and A2 have skillful prediction of Sahel precipitation and the associated ITCZ shift. The prediction skill of SST is generally lower in A2 than A1 especially over SO presumably due to the sparse surface pressure observations.
format	article
author	Xiaosong Yang Thomas L. Delworth Fanrong Zeng Liping Zhang William F. Cooke Matthew J. Harrison Anthony Rosati Seth Underwood Gilbert P. Compo Chesley McColl
author_facet	Xiaosong Yang Thomas L. Delworth Fanrong Zeng Liping Zhang William F. Cooke Matthew J. Harrison Anthony Rosati Seth Underwood Gilbert P. Compo Chesley McColl
author_sort	Xiaosong Yang
title	On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
title_short	On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
title_full	On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
title_fullStr	On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
title_full_unstemmed	On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment
title_sort	on the development of gfdl's decadal prediction system: initialization approaches and retrospective forecast assessment
publisher	American Geophysical Union (AGU)
publishDate	2021
url	https://doaj.org/article/8a54f3ef068a4f40bb7e718d367989a2
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On the Development of GFDL's Decadal Prediction System: Initialization Approaches and Retrospective Forecast Assessment

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